Effectiveness of Energy Conservation Techniques in Patients with COPD.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) might suffer from severe dyspnea, which importantly impacts on the performance of activities of daily living (ADL). Patient training of energy conservation techniques (ECTs) might be useful to improve the tolerance and execution of these ADL, but objective studies evaluating the effect of teaching ECTs on the metabolic equivalent of task (MET) in patients with COPD are sparse. OBJECTIVES: The aim of this study was to test the hypothesis that practicing ECTs after a 2-week ECT teaching period would reduce the energy expenditure (MET) in performing an activity in patients with severe COPD. METHODS: Energy expenditure was assessed with a gas exchange system (OxyconTM Mobile) during one out of five standardized ADL before and after a 2-week intervention period in which ECTs were taught. These ECTs comprised a good breathing technique, an ergonomic way of performing the activity, and the use of assistive devices. RESULTS: Thirty-two patients with COPD (mean FEV1: 39 ± 14%; female: n = 18; age: 68 ± 7 years) were included. A significantly lower MET (2.3 ± 0.6 to 2.1 ± 0.5; p < 0.05) and less desaturation (89.7 ± 5.2 vs. 91.1 ± 5.5% HbO2; p < 0.05) were seen while performing the same activity after the intervention. However, there was no significant difference in the time spent on the task performed (6.0 ± 3.9 vs. 6.7 ± 4.0 min; p > 0.05). CONCLUSIONS: A 2-week educative program on ECTs successfully reduces the energy spent for performing ADL relevant to the patient without any significant increase in the time spent on the activity.

Middle East Respiratory Syndrome Coronavirus: What Does a Radiologist Need to Know?

OBJECTIVE: The overarching goal of this article is to provide radiologists with the most up-to-date information regarding the underlying epidemiology, pathophysiology, clinical features, and imaging findings related to Middle East respiratory syndrome coronavirus (MERS-CoV), a potentially deadly new infection. CONCLUSION: An increased awareness of MERS-CoV and an understanding of the radiologic features of MERS-CoV can improve the early assessment and monitoring of this new infection. Radiologists can provide information based on chest radiographic and CT scores that can be helpful for patient management and predicting prognosis.

Acute Middle East Respiratory Syndrome Coronavirus: Temporal Lung Changes Observed on the Chest Radiographs of 55 Patients.

OBJECTIVE: The objective of our study was to describe lung changes on serial chest radiographs from patients infected with the acute Middle East respiratory syndrome corona-virus (MERS-CoV) and to compare the chest radiographic findings and final outcomes with those of health care workers (HCWs) infected with the same virus. Chest radiographic scores and comorbidities were also examined as indicators of a fatal outcome to determine their potential prognostic value. MATERIALS AND METHODS: Chest radiographs of 33 patients and 22 HCWs infected with MERS-CoV were examined for radiologic features indicative of disease and for evidence of radiographic deterioration and progression. Chest radiographic scores were estimated after dividing each lung into three zones. The scores (1 [mild] to 4 [severe]) for all six zones per chest radiographic examination were summed to provide a cumulative chest radiographic score (range, 0-24). Serial radiographs were also examined to assess for radiographic deterioration and progression from type 1 (mild) to type 4 (severe) disease. Multivariate logistic regression analysis, Kaplan-Meier survival curve analysis, and the Mann-Whitney U test were used to compare data of deceased patients with those of individuals who recovered to identify prognostic radiographic features. RESULTS: Ground-glass opacity was the most common abnormality (66%) followed by consolidation (18%). Overall mortality was 35% (19/55). Mortality was higher in the patient group (55%, 18/33) than in the HCW group (5%, 1/22). The mean chest radiographic score for deceased patients was significantly higher than that for those who recovered (13 ± 2.6 [SD] vs 5.8 ± 5.6, respectively; p = 0.001); in addition, higher rates of pneumothorax (deceased patients vs patients who recovered, 47% vs 0%; p = 0.001), pleural effusion (63% vs 14%; p = 0.001), and type 4 radiographic progression (63% vs 6%; p = 0.001) were seen in the deceased patients compared with those who recovered. Univariate and logistic regression analyses identified the chest radiographic score as an independent predictor of mortality (odds ratio [OR], 1.38; 95% CI, 1.07-1.77; p = 0.01). The number of comorbidities in the patient group (n = 33) was significantly higher than that in the HCW group (n = 22) (mean number of comorbidities, 1.90 ± 1.27 vs 0.17 ± 0.65, respectively; p = 0.001). The Kaplan-Meier analysis revealed a median survival time of 15 days (95% CI, 4-26 days). CONCLUSION: Ground-glass opacity in a peripheral location was the most common abnormality noted on chest radiographs. A higher chest radiographic score coupled with a high number of medical comorbidities was associated with a poor prognosis and higher mortality in those infected with MERS-CoV. Younger HCWs with few or no comorbidities had a higher survival rate.

CT correlation with outcomes in 15 patients with acute Middle East respiratory syndrome coronavirus.

OBJECTIVE: The purpose of this article is to retrospectively analyze chest CT findings for 15 patients with Middle East respiratory syndrome coronavirus and to identify features associated with survival. MATERIALS AND METHODS: Patients were assigned to group 1 if they died (n=9) and to group 2 if they made a full recovery (n=6). Two reviewers scored chest radiographs and CT examinations for segmental involvement, ground-glass opacities, consolidation, and interstitial thickening. RESULTS: Eight patients had ground-glass opacity (53%), five had ground-glass and consolidation in combination (33%), five had pleural effusion (33%), and four patients had interlobular thickening (27%). Of 281 CT findings, 151 (54%) were peripheral, 68 (24%) were central, and 62 (22%) had a mixed location. The number of involved lung segments was higher in group 1. The lower lobe was more commonly involved (mean, 12.2 segments) than in the upper and middle lobes combined (mean, 6.3 segments). The mean number of lung segments involved was 12.3 segments in group 1 and 3.4 segments in group 2. The CT lung score (mean±SD, 15.78±7.9 vs 7.3±5.7, p=0.003), chest radiographic score (20.8±1.7 vs 5.6±5.4; p=0.001), and mechanical ventilation duration (13.11±8.3 vs 0.5±1.2 days; p=0.002) were higher in group 1. All nine group 1 patients and three of six group 2 patients had pleural effusion (p=0.52). CONCLUSION: CT of patients with Middle East respiratory syndrome coronavirus predominantly showed ground-glass opacities, with peripheral lower lobe preference. Pleural effusion and higher CT lung and chest radiographic scores correlate with poor prognosis and short-term mortality.

Computed tomography virtual bronchoscopy: normal variants, pitfalls, and spectrum of common and rare pathology.

A broad spectrum of pathologies that involve the laryngotracheobronchial airway and imaging plays a crucial role in evaluating these abnormalities. Computed tomography with virtual bronchoscopy has been found to be very helpful in defining the location, extent, and nature of these lesions, and is increasingly being used even in patients with contraindications for fiberoptic bronchoscopy and laryngoscopy. Ionizing radiation, associated with virtual bronchoscopy, can be minimized by using low-dose multidetector computed tomography and hybrid iterative reconstruction techniques. Furthermore, retrospectively generated virtual bronchoscopy from a routinely acquired computed tomography data set eliminates additional cost and radiation. In the future, virtual bronchoscopy assisted with advanced navigational techniques will broaden the diagnostic and therapeutic landscape. This article presents the characteristic features of common and rare laryngotracheobronchial pathologies seen with virtual bronchoscopy.

Williams-Beuren syndrome: computed tomography imaging review.

Williams-Beuren syndrome (WBS) affects young infants and children. The underlying etiopathogenesis of this rare disease is due to the mutation of the elastin gene that is responsible for the elasticity of the arterial wall. As a result of inadequate elastin production, the major systemic arteries become abnormally rigid and can be manifested by an impediment to the blood flow. The most common cardiovascular abnormalities encountered in WBS are supravalvular aortic stenosis, pulmonary arterial stenosis, and mitral valve prolapse. Less frequently observed cardiovascular abnormalities include coarctation of the aorta, ventricular septal defect, patent ductus, subaortic stenosis, and hypertrophic cardiomyopathy. Coronary artery stenosis and severe impediment to the bi-ventricular outflow as a result of supravalvular aortic and pulmonary artery stenosis predispose patients to sudden death. Patients with progressed arterial stenosis and severe stenosis are likely to require intervention to prevent serious complications. Rarely, imaging findings may precede clinical presentation, which allows the radiologist to participate in the patient care. However, to be more prudent, the radiologist must be accustomed to the imaging characteristics of WBS as well as the patient's clinical information, which could raise the suspicion of WBS. We performed a retrospective analysis of all the available images from patients diagnosed with WBS in last 4 years at our institution, and present key imaging findings along with a review of the literature to summarize the clinically relevant features as demonstrated by multidetector computed tomography in WBS. Cross-sectional imaging plays a vital role in the diagnosis of WBS cases with equivocal clinical features. MDCT evaluation of complex cardiovascular abnormalities of WBS including coronary artery disease is feasible with modern MDCT scanners and in the future, this approach could provide accurate information for planning, navigation, and noninvasive assessment of the secondary arterial changes in WBS and thus reducing the dependence upon invasive contrast catherization techniques.

Normative MDCT cross-sectional data estimation of superior vena cava and innominate vein in growing children using age as a predictor.

This retrospective study aimed to determine the superior vena cava (SVC) and left innominate vein (INV) normative cross-sectional area in children noninvasively using age as a predictor and also to compare the correlation of the area measured with the diameter on multidetector computed tomography (MDCT). Analysis of the SVC-INV cross-sectional area was performed for 73 consecutive patients. The cross-sectional area of the SVC-INV was manually estimated. A regression analysis was performed for the cross-sectional area and age separately, and regression equations were compared. One-way analysis of variance (ANOVA) was performed to evaluate significant differences in the area means according to age groups. Regression analysis showed that age can be a predictor for the area of the SVC (50.6 mm(2) + 1.01 × age), te INV (48.3 mm(2) + 0.93 × age), and the left SVC-INV junction (47.2 mm(2) + 0.92 × age), with respective R(2) values of 93, 88 and 94%. The comparative evaluation of the cross-sectional area and the diameter measurement of SVC showed that the cross-sectional area was more closely associated with the increasing age of the cohort (R(2) of 68 vs. 61%) than the measured diameter. For a cohort of patients without congenital or acquired heart disease, MDCT can be used as a complementary test for a normative cross-sectional normogram area database of SVC-INV using age as a predictor.

Correlations between Spectra and Resistivity in Transition Metal Oxides.

A comparison between photoconductivity spectra and resistivity in two transition metal oxides, La2-xSrxCuO4 and La1-xSrxVO3, is presented. The resistivities ρ(T) for x < 0.05 in the cuprate and x < 0.28 in the vanadate are typical for single electron transfer. For T > 100 K, ρ(T) - ρ(0) ∼ T3/2. For higher dopings (x) the cuprate is a superconductor (x < 0.25) and the vanadate an ordinary metal. This tallies with the number of oxidation states and their spins when the electrons transfer locally. The insulator-metal transition and the vanishing of Cooper pairs are discussed in the conclusion.

Emplacement and 3D geometry of crustal-scale saucer-shaped intrusions in the Fennoscandian Shield.

Saucer-shaped intrusions of tens of meters to tens of kilometres across have been observed both from surface geological mapping and geophysical observations. However, there is only one location where they have been reported to extend c. 100 km laterally, and emplaced both in a sedimentary basin and the crystalline basement down to 12 km depth. The legacy BABEL offshore seismic data, acquired over the central Fennoscandian Shield in 1989, have been recovered and reprocessed with the main goal of focusing on this series of globally unique crustal-scale saucer-shaped intrusions present onshore and offshore below the Bothnian Sea. The intrusions (c. 1.25 Ga), emplaced in an extensional setting, are observed within both sedimentary rocks (<1.5 Ga) and in the crystalline basement (>1.5 Ga). They have oval shapes with diameters ranging 30-100 km. The reprocessed seismic data provide evidence of up-doming of the lower crust (representing the melt reservoir) below the intrusions that, in turn, are observed at different depths in addition to a steep seismically transparent zone interpreted to be a discordant feeder dyke system. Relative age constraints and correlation with onshore saucer-shaped intrusions of different size suggest that they are internally connected and fed by each other from deeper to shallower levels. We argue for a nested emplacement mechanism and against a controlling role by the overlying sedimentary basin as the saucer-shaped intrusions are emplaced in both the sedimentary rocks as well as in the underlying crystalline basement. The interplay between magma pressure and overburden pressure, as well as the, at the time, ambient stress regime, are responsible for their extensive extent and rather constant thicknesses (c. 100-300 m). Saucer-shaped intrusions may therefore be present elsewhere in the crystalline basement to the same extent as observed in this study some of which are a significant source of raw materials.

Trapped water molecule in the charge separation of a bacterial reaction center.

Low-frequency oscillations in the absorption spectrum at 1020 nm, connected to the primary charge separation process in Rhodobacter sphaeroides, have been shown by Yakovlev et al. to be caused by rotational motion of an interstitial water molecule called "water-A". The same water molecule was shown by Potter et al. to increase the rate of charge separation by a factor of 8. We have carried out geometry optimization of water-A and its nearest atoms in the protein pocket, using density functional theory (DFT). There are strong hydrogen bonds to the axial imidazol group of the B part of the special pair (P=PAPB) and to the keto carbonyl group of ring V of the accessory chlorophyll (BA). Rotation of water-A is thus impossible in the electronic ground state. We have tried to support our speculations on other possible mechanisms by calculations. The P(+)BA(-) charge transfer state is stabilized by proton transfer from water-A and simultaneous proton transfer from the axial group of PB to water-A. After double proton transfer the hydrogen bond to the keto group disappears whereby a possibility opens up for almost free water rotation. The results therefore would explain the 32 cm(-1) oscillation of Yakovlev et al. The proposed mechanism assumes, however, that the general assumption that the activation energy disappears in the primary charge separation of bacterial photosynthesis, holds also for this special case.

Energy cost of physical activities in children: validation of SenseWear Armband.

PURPOSE: To examine the validity of SenseWear Pro2 Armband in assessing energy cost of physical activities in children, and to contribute with values of energy costs in an overview of physical activities in children. METHODS: Energy cost was assessed by SenseWear Pro2 Armband in 20 healthy children, 11-13 yr, while lying down resting, sitting playing games on mobile phone, stepping up and down on a step board, bicycling on a stationary bike, jumping on a trampoline, playing basketball, and walking/running on a treadmill at the speeds 2, 3, 4, 5, 6, 7, 8, and 10 km x h(-1). During these activities, energy cost was also assessed from VO2 and VCO2 measured by Oxycon Mobile portable metabolic system, which was used as criterion method. RESULTS: The difference in energy cost between SenseWear Pro2 Armband and Oxycon Mobile was -0.7 (0.5) (P < 0.001) for resting, -2.0 (0.9) (P < 0.001) for playing games on mobile phone, -6.6 (2.3) (P < 0.001) for stepping on the step board, -12.0 (3.7) (P < 0.001) for bicycling, -2.7 (11.9) (P = 0.34) for jumping on the trampoline, and -14.8 (6.4) kJ x min(-1) (P < 0.001) for playing basketball. The difference in energy cost between SenseWear Pro2 Armband and Oxycon Mobile for increasing treadmill speed was 1.3 (3.1) (P = 0.048), 0.1 (2.9) (P = 0.82), -1.2 (2.6) (P = 0.049), -1.6 (3.2) (P = 0.044), -3.1 (3.7) (P = 0.0013), -4.9 (3.7) (P < 0.001), -5.3 (3.7) (P < 0.001), and -11.1 (3.5) kJ x min(-1) (P < 0.001). CONCLUSIONS: SenseWear Pro2 Armband underestimated energy cost of most activities in this study, an underestimation that increased with increased physical activity intensity. A table of energy costs (MET values) of physical activities in children measured by indirect calorimetry is presented as an initiation of the creation of a compendium of physical activities in children.

Follow-up chest radiographic findings in patients with MERS-CoV after recovery.

PURPOSE: To evaluate the follow-up chest radiographic findings in patients with Middle East respiratory syndrome coronavirus (MERS-CoV) who were discharged from the hospital following improved clinical symptoms. MATERIALS AND METHODS: Thirty-six consecutive patients (9 men, 27 women; age range 21-73 years, mean ± SD 42.5 ± 14.5 years) with confirmed MERS-CoV underwent follow-up chest radiographs after recovery from MERS-CoV. The 36 chest radiographs were obtained at 32 to 230 days with a median follow-up of 43 days. The reviewers systemically evaluated the follow-up chest radiographs from 36 patients for lung parenchymal, airway, pleural, hilar and mediastinal abnormalities. Lung parenchyma and airways were assessed for consolidation, ground-glass opacity (GGO), nodular opacity and reticular opacity (i.e., fibrosis). Follow-up chest radiographs were also evaluated for pleural thickening, pleural effusion, pneumothorax and lymphadenopathy. Patients were categorized into two groups: group 1 (no evidence of lung fibrosis) and group 2 (chest radiographic evidence of lung fibrosis) for comparative analysis. Patient demographics, length of ventilations days, number of intensive care unit (ICU) admission days, chest radiographic score, chest radiographic deterioration pattern (Types 1-4) and peak lactate dehydrogenase level were compared between the two groups using the student t-test, Mann-Whitney U test and Fisher's exact test. RESULTS: Follow-up chest radiographs were normal in 23 out of 36 (64%) patients. Among the patients with abnormal chest radiographs (13/36, 36%), the following were found: lung fibrosis in 12 (33%) patients GGO in 2 (5.5%) patients, and pleural thickening in 2 (5.5%) patients. Patients with lung fibrosis had significantly greater number of ICU admission days (19 ± 8.7 days; P value = 0.001), older age (50.6 ± 12.6 years; P value = 0.02), higher chest radiographic scores [10 (0-15.3); P value = 0.04] and higher peak lactate dehydrogenase levels (315-370 U/L; P value = 0.001) when compared to patients without lung fibrosis. CONCLUSION: Lung fibrosis may develop in a substantial number of patients who have recovered from Middle East respiratory syndrome coronavirus (MERS-CoV). Significantly greater number of ICU admission days, older age, higher chest radiographic scores, chest radiographic deterioration patterns and peak lactate dehydrogenase levels were noted in the patients with lung fibrosis on follow-up chest radiographs after recovery from MERS-CoV.

Validity of the ActiReg system in assessing energy requirement in chronic obstructive pulmonary disease patients.

BACKGROUND & AIMS: Malnutrition and weight loss are common in patients with chronic obstructive pulmonary disease (COPD) and effective nutritional support relies on accurate assessment of energy requirement. This could only be performed by measuring energy expenditure using objective methods. The aim of this study was to examine the validity of the ActiReg system in assessing energy requirement in non-hospitalized patients with severe COPD, using doubly labelled water (DLW) as criterion method. METHODS: Total energy expenditure (TEE) was assessed from 14 days DLW analysis in 13 patients. During the first 7 days TEE was simultaneously assessed using the ActiReg system, combining measured resting energy expenditure (REE) with physical activity monitoring. RESULTS: A difference of -88 (782) kJ d(-1) (P = 0.69) was observed between the ActiReg system and DLW. REE explained 52% of the variation in TEE from DLW. Adding physical activity energy expenditure from the ActiReg system (PAEE(AR) = TEE(AR)-REE) increased the explained variation in TEE from DLW with 16%. CONCLUSIONS: The ActiReg system is valid in assessing energy requirement in non-hospitalized patients with severe COPD. The unique feature of being able to discriminate within both the low intensity activity range and moderate-to-high intensity activity range makes the ActiReg system a valuable tool in clinical nutritional support.

Single breath N2-test and exhaled nitric oxide in men.

The N(2) slope is an index of inhomogeneous distribution of ventilation and has been suggested to be suited for early testing of chronic obstructive pulmonary disease (COPD) in smokers. The aim of the present study was to examine the association between the fraction of exhaled nitric oxide (FENO) and the N(2) slope in a random population of smoking and non-smoking men. Altogether 57 subjects were included in the study, 24 never-smokers, seven ex-smokers and 26 current smokers. Subjects were examined twice, in 1995 when they regarded themselves as healthy, and in a follow-up in 2001. Spirometry, N(2) slope and high-resolution computed tomography (HRCT) were performed in 1995 while the follow-up examination included also measurement of FENO. The FENO value was significantly lower and the N(2) slope higher in current smokers. In smokers but not in never- or ex-smokers FENO was correlated to the difference in N(2) slope between 1995 and 2001 (r(s)=0.49, P=0.01). We analysed the data by multiple linear regression adjusted for smoking, mild respiratory symptoms and inhaled steroids. There were significant associations between FENO and the N(2) slope both in 1995 and in 2001. The strongest association was found to exist with the change in N(2) slope during these years. Sixteen of the subjects could be classified as having COPD, six with mild and ten with moderate COPD. There was a trend for an increase in N(2) slope with increased severity of COPD; among subjects with no COPD the N(2) slope in 2001 was 2.3% N(2)/L, and those with mild and moderate COPD had 2.5% N(2)/L and 3.9% N(2)/L, respectively (P=0.0004). No such trend was seen for FENO (17.8, 15.5 and 20.3 parts per billion (ppb), respectively, P=0.8). The results show that FENO is associated with the N(2) slope, indicating that FENO reflects inflammatory changes in the peripheral airways of both non-smoking and smoking subjects.

Primary photoprocess in vision: minimal motion to reach the photo- and bathorhodopsin intermediates.

According to time-resolved spectroscopic measurements, the initial step of the photoreaction of rhodopsin occurs with a time constant of approximately 200 fs. The whole or a part of the retinal molecule cannot move any significant distance in such a short time. In this paper, we propose instead a minimal motion that accomplishes the important task of guiding the molecule to a configuration where it can decay to the ground-state surface, with a minimal loss of strain energy. This motion is proposed to involve a -90 degrees twisting of the C11=C12 double bond and a simultaneous twisting around two other double bonds in retinal to minimize the geometrical changes along the reaction path. The ONIOM method (complete active space self-consistent field for retinal and AMBER for the peptides) is used in a chromophore-cavity model to elucidate and confirm important features of the mechanism. The potential energy surface (PES) obtained according to the proposed mechanism show all of the characteristics of a fast photoreaction, meaning a downhill reaction path from the Franck-Condon point to an avoided crossing between S(1) and S(0). In this motion, only a few carbon and hydrogen atoms move more than 0.3 A, and the retinal structure is conserved in the protein cavity. We propose that the photorhodopsin intermediate is a retinal molecule formed on the excited-state PES. Bathorhodopsin, however, is a ground-state intermediate, still located inside the protein cavity.

Excitonic states in photosystem II reaction center.

The excited states of a structurally well-determined photosystem II (PSII) reaction center are obtained using an effective Hamiltonian for the interaction between the Q(y) states. The latter are calculated using the time-dependent density functional theory (DFT) method in DFT-optimized geometries, but with conserved side group orientations. Of particular importance is the orientation of the vinyl group of ring I. Couplings are calculated using actual transition charge distributions via the INDO/S model. Good agreement with experimental spectra is obtained. The lowest excited state is mainly located on the inactive B-side, but with a large component on P(A) too, making charge separation to H(A) possible at low temperature. The "trap state" and triplet state are localized on the inactive B-side. Since the spin singlet Q(y) states of the reaction center are all within a rather small energy range, the state with the highest component of B(A)*, on the blue side of the Q(y) absorption, has a rather high Boltzmann population at room temperature. The charge-transfer states, however, have a rather large spread and cannot be calculated accurately at present. The orientation of the phytyl chains is important and has as a consequence that the energy for the charge-separated B(A)+ H(A)- state is significantly lower than the corresponding state on the B-side. It follows that the B(A)* and P(A)* states are both possible origins for a fast charge separation in PSII.

Body composition by bioelectrical impedance predicts mortality in chronic obstructive pulmonary disease patients.

Pulmonary rehabilitation is recommended in international treatment guidelines for chronic obstructive pulmonary disease (COPD). No one has however studied the effect on long-term mortality. The aim of the current study was to study the mortality in a sample of patients with severe COPD included in a 1-year multidisciplinary rehabilitation program. Body composition was assessed at baseline using bioelectrical impedance. Mortality was studied in 86 patients using the Cox proportional hazards model. Forty-seven (55%) of the patients died during the mean follow-up time which was almost 6 years. Risk of mortality increased with increasing age, increasing number of hospital days the year before inclusion and men had higher mortality risk than women. The mortality risk decreased with increasing % reference body weight, increasing fat-free mass index (FFMI), increasing FEV(1) and increasing 6-min walking distance. Gender, age and FFMI continued to be statistical significant predictors of mortality when controlling for the other baseline variables in a multivariate analysis. To conclude, body composition, measured by bioelectrical impedance and presented as FFMI, is an independent predictor of mortality in COPD patients.

Surfactant Protein A in Exhaled Endogenous Particles Is Decreased in Chronic Obstructive Pulmonary Disease (COPD) Patients: A Pilot Study.

BACKGROUND: Exhaled, endogenous particles are formed from the epithelial lining fluid in small airways, where surfactant protein A (SP-A) plays an important role in pulmonary host defense. Based on the knowledge that chronic obstructive pulmonary disease (COPD) starts in the small airway epithelium, we hypothesized that chronic inflammation modulates peripheral exhaled particle SP-A and albumin levels. The main objective of this explorative study was to compare the SP-A and albumin contents in exhaled particles from patients with COPD and healthy subjects and to determine exhaled particle number concentrations. METHODS: Patients with stable COPD ranging from moderate to very severe (n = 13), and healthy non-smoking subjects (n = 12) were studied. Subjects performed repeated breath maneuvers allowing for airway closure and re-opening, and exhaled particles were optically counted and collected on a membrane using the novel PExA® instrument setup. Immunoassays were used to quantify SP-A and albumin. RESULTS: COPD patients exhibited significantly lower SP-A mass content of the exhaled particles (2.7 vs. 3.9 weight percent, p = 0.036) and lower particle number concentration (p<0.0001) than healthy subjects. Albumin mass contents were similar for both groups. CONCLUSIONS: Decreased levels of SP-A may lead to impaired host defense functions of surfactant in the airways, contributing to increased susceptibility to COPD exacerbations. SP-A in exhaled particles from small airways may represent a promising non-invasive biomarker of disease in COPD patients.